According to the National Stroke Association, 550,000 Americans suffer a new or recurrent stroke each year. Of these patients, nineteen percent (19%) to thirty eight percent (38%), or about 150,000, will aspirate, which is defined as the taking of foreign material, such as saliva and ingested food, into the lungs. Aspiration increases the chances of contracting pneumonia by 20-fold and is believed responsible for approximately 40,000 deaths following a stroke every year in the United States alone.
Aspiration results from several factors, including insufficient laryngeal elevation, poor coordination of pharyngeal muscular contraction, and/or insufficient or untimely and poorly adjusted closure of the vocal folds to protect the airway. If standard therapies fail, the patient may not be allowed to take food by mouth and tubes may have to be placed into the intestinal tract to bypass swallowing. Current options to protect the airways involve irreversible and destructive surgery of the upper airway. These often reduce the patient's quality of life.
Swallowing is normally initiated according to a series of steps of the oral phase such as the introduction of food into the mouth, mastication, posterior tongue thrusting, and so on. Once the bolus is present in the pharynx, however, the process becomes fully reflexogenic as it automatically proceeds until an end point represented by laryngeal closure and bolus diversion through the opening upper esophageal sphincter acting as a suction pump.
While brain plasticity allows many patients to regain workable function within a few weeks, aspiration persists beyond this period in approximately one half of the cases. Some treatments include special risk-reduction diets with varied consistency, composition, and calorie counts delivered in conjunction with passive measures (e.g. chin tuck, head turn, double supraglottic swallow, supersupraglottic swallow, the Mendelsohn maneuver, and so on). These patients often require a tracheotomy to secure pulmonary toilet and enteral feedings (i.e. not natural, by external means into the gut) such as through tube gastrostomy or jejunostomy to deliver appropriate caloric intake. Despite such precautions, pneumonia will still occur in approximately twenty percent (20%) of the cases.
Whatever the nature of the disruption affecting the pharyngeal sequence leading to laryngeal incompetence after various neurological assaults and not alleviated by non-invasive approaches, therapy has focused on surgical separation between the airway and the alimentary tract to either seal the airway or to divert the passage of ingested material away from the incompetent laryngeal valve and prevent flooding of the lungs. While there has traditionally been no alternative, these interventions have a major disadvantage in that they must mutilate normal organ systems, i.e., the larynx and the pharynx, often irreversibly, to be clinically effective. Moreover, these operations have an additional disadvantage in that they lack the dynamic qualities required for the restoration of the mutually exclusive functions of vocal fold adduction, which is necessary for speaking and swallowing, and abduction (opening of the vocal folds), which is necessary for breathing, thus imposing a choice between airway safety and voice production It is, therefore, desirable to have a simple, dynamic method and system that does not mutilate normal organs such as the larynx and the pharynx to restore the ability to swallow in humans or animals.